Contractor Ramon Neyra paints a fence at a job site in El Cerrito, Calif. on Friday, August 24, 2007. Now a U.S. citizen, Neyra worked for years as an illegal immigrant. PAUL CHINN/The Chronicle
**Ramon Neyra MANDATORY CREDIT FOR PHOTOGRAPHER AND S.F. CHRONICLE/NO SALES - MAGS OUT

Jorge S., an East Bay grocery store clerk, worries about his family's future if the Bush administration follows through with its declaration this month to crack down on employers who fail to verify the legal status of their workers.

"Everyone at the store is worried about it. We're all in the same boat," said Jorge, 53, who invented a Social Security number to get hired eight years ago and would not give his last name for fear of losing his job. "I'd be in a very difficult situation if I lose my job."

Jorge is among hundreds of thousands of illegal immigrants in Northern California who are working without proper authorization. Immigration experts say that American jobs are the biggest magnet for illegal immigrants and that the new policy of enforcing a 20-year-old law barring employers from hiring undocumented workers is an important step in reducing illegal border crossings.

"It's the only thing that could have a deterrent effect," said Wayne Cornelius, director of the Center for Comparative Immigration Studies at UC San Diego. "The overwhelming incentive for coming here is the prospect of being employed in jobs that invariably pay far more than low-skilled jobs pay in Mexico or other sending countries."

Some advocates of tougher worksite enforcement say that if the new policy is seriously enforced, it could not only deter prospective foreign workers from coming without authorization but make life so miserable for illegal immigrants already in the United States that they will decide to leave.

"You'll see it become much more difficult for illegal immigrants to get mainstream jobs," said Mark Krikorian, executive director of the Center for Immigration Studies in Washington, which advocates reduced immigration, both legal and illegal. "There's no question we'd have a significant level of self-deportation if the illegal immigrants came to expect that enforcement was here to stay."

The new rules, announced Aug. 10 by Michael Chertoff, secretary of the Department of Homeland Security, will require employers to fire workers who are unable to clear up problems with their Social Security numbers within 90 days after they've been notified in a "no-match" letter. Employers who don't comply will face a fine of at least $2,200 and possible criminal penalties.

Employer associations say they are instructing their members on how to comply with the law. But they worry that if they have to let workers go, they could face a labor shortage.

"I think this will hurt the California economy probably more than any other state," said Kevin Westlye, director of the Golden Gate Restaurant Association. "There will be an impact on the economy, but also on those individuals. There are 2 million undocumented workers in the state of California and generally these are good, hard-working people."

Peninsula resident Silvia Esparza, 44, said she already finds life as an undocumented immigrant pretty tough. She lives with a perpetual fear of being deported, has no driver's license and no possibility of establishing credit. Though she has lived in the Bay Area for 17 years and works for a mail-order cleaning products company, she said she would give it up and return to Mexico if she lost her job over a no-match letter.

"I would go back to my country, but that's because I don't have the problem of having my children here," said Esparza, who sent her four kids to live with her parents in Baja California several years ago to protect them from the influence of American gangs. "I'm a hard worker, so I know I could survive. But I don't know if my kids would be able to continue their education. I've put the two oldest through university."

For Jorge and other illegal immigrants who are raising their children in the United States, the equation is different.

"I would look for other work, maybe work for myself doing gardening, home repairs, window washing," said the father of three, whose sister, a U.S. citizen, applied nine years ago to sponsor him for legal residency. The current green card waiting period for a Mexican sibling of a U.S. citizen is 17 years.

"We're still waiting," said Jorge. "I just tell my kids to keep studying and not to lose hope."

The administration's new policy intensifies an approach already in motion by U.S. Immigration and Customs Enforcement, which has stepped up criminal prosecutions of companies that conspire to employ illegal immigrants. In the first 10 months of the current fiscal year, ICE made 745 criminal arrests and 3,561 administrative arrests of employers and employees, eight times as many as in all of 2002.

"No employer, regardless of industry or location, is immune from complying with the nation's laws," said ICE chief Julie Myers earlier this month.

Ramón Neyra, a Nicaraguan-born contractor who lives in Oakland and earned his U.S. citizenship last year, counts himself lucky that his nationality allowed him to escape the shadow world of living as an illegal immigrant.

Neyra, 45, fled Nicaragua's civil war and spent years in the United States working under-the-table construction jobs. But a 1997 law offered legal residence to many Nicaraguan expatriates, and after more than a decade Neyra was able to bring his wife and two daughters to California.

"I know a lot of people who live in constant fear that they'll be deported," he said. "They're all honest people who work very hard, as I did when I came here. After 18 years here I employ three people every day, I have my own business, my own house. I consider that I've been successful. And I know that these people, if you give them the opportunity, they will be successful, too."

In the United States, illegal immigrants number about 12 million and make up an estimated 5 percent of the civilian workforce, according to the Pew Hispanic Center.

Public opinion polls have shown that a solid majority of Americans favor offering undocumented immigrants a way to earn legal status, but they also want to see toughened immigration enforcement.

A Time magazine poll in March, for instance, found 78 percent support for "allowing illegal immigrants now in this country to earn U.S. citizenship if they learn to speak English, have a job and pay taxes." Forty-seven percent of those polled also said they supported deportation of all undocumented workers.

A Zogby America International poll released in May found 69 percent public approval for a strict crackdown in illegal immigration, while 50 percent approved granting green cards to undocumented immigrants and putting them on the path to citizenship.

The hotly debated question in Washington is which to tackle first. The Bush administration heightened its focus on enforcement after Congress failed this summer, for the second consecutive year, to reach an agreement on reworking the nation's immigration laws.

But Westlye and others say the administration is putting the cart before the horse. Mark Silverman, a staff attorney at the Immigrant Legal Resource Center in San Francisco, believes the government must first legalize unauthorized immigrants and create a way for future foreign workers to come lawfully.

"Then you can say we're going to ... enforce the laws against hiring undocumented workers really strictly," he said. Otherwise, "they will be driven into the underground economy. The theory is that people will go home, but I think it will be a very small percentage."

Krikorian of the Center for Immigration Studies argues that tough workplace enforcement must come first, combined with stepped up deportations and increased involvement of state and local officials in enforcing immigration law.

"Over five years, we could probably reduce the illegal population by half. ... Once we do that, we could talk about what to do with the rest," he said. "For the majority of illegal workers who gave stolen or fake Social Security numbers, they shouldn't be working. It's as simple as that."

Rules at a glance

What's new: Rules announced this month by the Bush administration will require employers to fire employees unable to clear up problems with their Social Security numbers 90 days after they've been notified of such discrepancies in what are called "no-match letters."

What it means: Hiring undocumented workers has been illegal for two decades, but until now, employers were not held liable for fraudulent documents. Employers who fail to comply will face fines and sanctions.